Umbilical cord blood-derived CD133+ cells exhibit the ability to differentiate into endothelial cells and induce new blood vessel growth. Hypoxia-inducible factor-1 (HIF-1), a regulator of hypoxia or the hypoxia-mimetic agent response, actives the SDF-1/CXCR4 signaling pathway and thus plays an important role in angiogenesis in-vivo. In this study we aim to investigate whether CD133+ cells enhance angiogenic ability through hypoxia or CoCl2 in vitro. The CD133+ cells were cultured in normoxia (20 Percent O2), hypoxia (10 Percent O2, 3 Percent O2), or in various concentrations of CoCl2 (50 microM/L, 100 microM/L, 200 microM/L) and subjected to in vitro flow cytometric analysis, tubule formation, as well as migration and proliferation assays. The results demonstrate that both environmental hypoxia and CoCl2 induced hypoxia result in significantly increased CD133+ cell migration, proliferation, and tubule-like structure formation compared with normoxia culture conditions. The HIF-1a, SDF-1, and VEGF protein and gene expression level in conditions of hypoxia is higher than that found in normaxia conditions. Collectively, these data suggest that angiogenic potential of CD133+ cells is influenced by hypoxia or a hypoxia mimetic agent in vitro.
[Show abstract][Hide abstract] ABSTRACT: There is a continuing need to develop scaffold materials that can promote vascularisation throughout the tissue engineered construct. This study investigated the effect of cobalt oxide (CoO) doped into titanium phosphate glasses on material properties, biocompatibility and vascular endothelial growth factor (VEGF) secretion by osteoblastic MG63 cells. Glasses composed of (P2O5)45(Na2O)20(TiO2)05(CaO)30-x(CoO)x(x=0, 5, 10, and 15mol%) were fabricated and the effect of Co on physicochemical properties including density, glass transition temperature (Tg), degradation rate, ion release, and pH changes was assessed. The results showed that incorporation of CoO into the glass system produced an increase in density with little change in Tg. It was then confirmed that the pH did not change significantly when CoO was incorporated in the glass, and stayed constant at around 6.5-7.0 throughout the dissolution study period of 336h. Ion release results followed a specific pattern with increasing amounts of CoO. In general, although incorporation of CoO into a titanium phosphate glass increased its density, other bulk and surface properties of the glass did not show any significant changes. Cell culture studies performed using MG63 cells over a 7-day period indicated that the glasses provide a stable surface for cell attachment and are biocompatible. Furthermore, VEGF secretion was significantly enhanced on all glasses compared with standard tissue culture plastic and Co doping enhanced this effect further. In conclusion, the developed Co-doped glasses are stable and biocompatible and thus offer enhanced potential for engineering vascularized tissue.
[Show abstract][Hide abstract] ABSTRACT: Objective
Low oxygen tension is one of the crucial factors of the stem cell niche. However, the long term hypoxic culture of stem cells is difficult and requires special equipment. In this study, we investigated whether mimicking hypoxia using cobalt chloride (CoCl2) could maintain human periodontal ligament (HPDL) cell stemness.
HPDL cells were treated with either 50 or 100 μM CoCl2. Cell proliferation was determined by an MTT assay. The mRNA expression of stem cell marker and osteogenic associated genes were analyzed by RT-PCR and Real-time PCR. Osteogenic differentiation was determined by assaying alkaline phosphatase activity and in vitro mineralization.
The results showed that the CoCl2 supplementation had no effect on cell proliferation. CoCl2 treatment increased the mRNA expression of the embryonic stem cell markers REX1 and OCT4. Culturing HDPL cells in osteogenic medium containing CoCl2 resulted in a decrease in alkaline phosphatase activity, down-regulation of osteogenic associated gene expression, and suppression of mineralization. The use of Apigenin, a HIF-1α inhibitor, indicated that CoCl2 might inhibit osteogenic differentiation through a HIF-1α dependent mechanism.
This study shows that CoCl2 treatment can induce stem cell marker expression and inhibit the osteoblastic differentiation of HPDL cells. These findings suggest the potential application of CoCl2 for maintaining the stem cell state in the laboratory.
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